I have a question about radio waves. If there was an ET civilization out there broadcasting in the EM spectrum exactly like we do, how far away could it be where we would still be able to detect it? (naturally this assumes it transmitted at the proper time for us to receive the signal, ie 40 years ago if it is 40 light years away). I am just curious as to how far away a civilization like us could be and still be able to detect OUR signals given that they have similar capabilities. I realize that an advanced civilization may be much better at it than we are.